1. Field of the Invention
This invention relates to new and useful improvements in refrigeration systems having a metering device such as an expansion valve, a condenser, a compressor, and an evaporator where means is provided to cool the liquid flowing from the condenser to the metering or expansion device controlling refrigerant flow to the evaporator.
2. Brief Description of the Prior Art
Refrigeration systems consume a significant portion of all electrical energy generated in the United States. Because the systems often have to operate at high ambient temperatures, they seldom operate at the most efficient level. One problem which causes a portion of this inefficiency is the formation of vapor in the liquid refrigerant line between the condenser and the metering device. In many systems, there is a problem of heat absorption in the conduit between the condenser and the metering device.
If the ambient temperature is high vapor may form in the conduit. Additionally, pressure reductions in the line as a result of friction or decreases in the head pressure as the refrigerant moves further from the compressor and condenser can contribute to the formation of vapor. Because the metering or expansion devices generally are sized for passing only liquid, any vapor in the line significantly decreases the efficiency of the system by decreasing the amount of liquid which can pass through the metering device to the evaporator.
Various approaches and procedures have been developed and utilized to overcome the problem of vapor formation. One approach involves increasing the pressure in the liquid refrigerant line to a point that no vapor will form under most or all operating conditions which the system is likely to encounter. However, this requires a larger compressor than would otherwise be necessary, resulting in a greater use of power to run the compressor.
Another approach is disclosed in U.S. Pat. No. 4,259,848 to Voigt. In this system, vapor formed by exposure of the liquid refrigerant conduit to ambient conditions is withdrawn from a receiver by a dual suction compressor, and the refrigerant approaching the expansion valve is adiabatically cooled to liquefy vapor formed by withdrawal of vaporized refrigerant from the high pressure portion of the circuit. This system has several drawbacks. It cannot be used effectively on refrigeration systems having a hot gas defrost; a complicated valving between the receiver and the compressor is required to control the flow of vaporized refrigerant from the high pressure line back to the compressor; and the metering device must be an expansion valve.
Accordingly, it would be a significant advancement in the art to have a fixed, mechanical condensing final condenser/cooler which could be used in closed circuit refrigeration systems to cool the liquid refrigerant before passing through the metering or expansion device. It would be particularly advantageous to provide such a system which is simple in construction and operation, and which is effective. Such a system is disclosed and claimed herein.